Book excerpt: It is vital for countries to monitor their population’s diets to inform actions toward improving the health of people and the planet. The healthiness of diets must be tracked in global frameworks, such as the Sustainable Development Goals (SDGs), to help monitor how the world’s population is faring. Currently, few countries regularly assess diets and there are no dietary indicators in global monitoring frameworks. Recognizing the importance of diets for health and the lack of consensus on how to measure and monitor healthy diets at scale, FAO, UNICEF and WHO joined forces to chart a way forward via the Healthy Diets Monitoring Initiative (HDMI). The joint mission of the HDMI is to enable national and global decision-makers and stakeholders to monitor and achieve healthy diets for people and the planet. The current guidance document is focused on healthy diets for healthy people. This version of the document provides an overview of the range of purposes for measuring the healthiness of diets and offers examples of the dietary assessment methods and types of dietary intake data, surveys and metrics that are currently available to monitor healthy diets.